Abstract
The tonoplast of isolated vacuoles from photoautotrophic suspension cells of Chenopodium rubrum L. was studied by means of the patch-clamp technique. In a symmetrical K+ concentration of 46 mM, similar to in vivo conditions, the tonoplast displayed a membrane potential near zero and a linear current-voltage relationship with a mean slope of 1.0 S/m2. ATP at 2 mM hyperpolarized the tonoplast (vacuole positive) by 15-20 mV and, in a parallel experiment, acidified the vacuole (outside pH 7.0) to pH 5.0, as monitored by accumulation of acridine orange. Analysis of the voltage-clamp current indicates a 2-fold, ATP-dependent increase of the membrane capacitance, from 4 to 8 mF/m2, and an ATP-independent, unidentified ion channel having a mean opening time of about 5 msec and a conductivity of 0.5-1.0 pS.
Keywords: patch-clamp technique, membrane ATPase, current-voltage analysis, ion channel
Full text
PDF
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Benz R., Zimmermann U. Evidence for the presence of mobile charges in the cell membrane of Valonia utricularis. Biophys J. 1983 Jul;43(1):13–26. doi: 10.1016/S0006-3495(83)84318-5. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Coster H. G. Turgor pressure sensing in plant cell membranes. Plant Physiol. 1976 Nov;58(5):636–643. doi: 10.1104/pp.58.5.636. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Hamill O. P., Marty A., Neher E., Sakmann B., Sigworth F. J. Improved patch-clamp techniques for high-resolution current recording from cells and cell-free membrane patches. Pflugers Arch. 1981 Aug;391(2):85–100. doi: 10.1007/BF00656997. [DOI] [PubMed] [Google Scholar]
- Neher E., Stevens C. F. Conductance fluctuations and ionic pores in membranes. Annu Rev Biophys Bioeng. 1977;6:345–381. doi: 10.1146/annurev.bb.06.060177.002021. [DOI] [PubMed] [Google Scholar]